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Mission News

Working atop a range of Martian hills, NASA's Spirit rover is rewarding
researchers with tempting scenes filled with evidence of past planet
environments.

"When the images came down and we could see horizon all the way around,
that was every bit as exhilarating as getting to the top of any mountain
I've climbed on Earth," said Chris Leger, a rover planner at NASA's Jet
Propulsion Laboratory, Pasadena, Calif.

Image right: This mini-panorama was taken by Spirit on Aug. 23, 2005, just as the rover finally completed its intrepid climb up "Husband Hill." The summit appears to be a windswept plateau of scattered rocks, little sand dunes and small exposures of outcrop. Image credit: NASA/JPL-Caltech/Cornell.+ Larger image+ More images from Spirit

The summit sits 82 meters (269 feet) above the edge of the surrounding
plains. It is 106 meters (348 feet) higher than the site where Spirit landed
nearly 20 months ago. Spirit and twin rover, Opportunity, successfully
completed their three-month prime missions in April 2004. They have inspected
dozens of rocks and soil targets since then, continuing their pursuit of
geological evidence about formerly wet conditions on Mars.

"Spirit has climbed to the hilltop and looked over the other side, but
NASA did not do this just to say we can do it. The Mars rovers are addressing
fundamental questions about Martian history and planetary environments," said
NASA's Mars Exploration Program Director Doug McCuistion.

The crest of "Husband Hill" offers Spirit's views of possible routes into a
basin to the south with apparently layered outcrops. Shortly after Spirit landed,
it observed a cluster of seven hills about 3 kilometers (2 miles) east of its landing
site. NASA proposed naming the range "Columbia Hills" in tribute to the last
crew of Space Shuttle Columbia. The tallest of the hills commemorates Rick
Husband, Columbia's commander.

Volcanic rocks covering the plain Spirit crossed on its way to the hills bore
evidence of only slight alteration by water. When Spirit reached the base of the
hills five months after landing, it immediately began finding rocks with wetter histories.

"This climb was motivated by science," said Steve Squyres of Cornell University,
Ithaca, N.Y. Squyres is principal investigator for the rovers' science instruments.
"Every time Spirit has gained altitude, we've found different rock types. Also,
we're doing what any field geologist would do in an area like this: climbing to a
good vantage point for plotting a route."

Researchers are viewing possible routes south to apparently layered ledges and to
a feature dubbed "home plate," which might be a plateau of older rock or a
filled-in crater.

The landing site and the Columbia Hills are within Gusev Crater, a bowl about
150 kilometers (95 miles) in diameter. The crater was selected as the landing
site for the Spirit rover because the shape of the terrain suggests the crater
once held a lake. Volcanic deposits appear to have covered any sign of ancient
lakebed geology out on the plain, but scientists say the hills expose older
layers that have been lifted and tipped by a meteorite impact or other event.

"We're finding abundant evidence for alteration of rocks in a water environment,"
said Ray Arvidson of Washington University, St. Louis, Mo. Arvidson is deputy
principal investigator for the rovers' science instruments. "What we want to do
is figure out which layers were on top of which other layers. To do that it has
been helpful to keep climbing for good views of how the layers are tilted to
varying degrees. Understanding the sequence of layers is equivalent to having a
deep drill core from drilling beneath the plains."